1. Field of the invention
This invention relates to a process for the production of light-colored surfactants, in which the surfactants are stabilized before bleaching by addition of antioxidants.
2. Statement of Related Art
Most surface-active compounds of the anionic surfactant type, but also certain nonionic surfactants, such as alkyl oligoglycosides for example, are dark in color from their production, for example as a result of oxidation and condensation processes. Although this discoloration has little or no adverse effect on the performance properties of the compounds, only those compounds which have been lightened in color by subsequent bleaching are suitable for subsequent processing on aesthetic grounds. Peroxygen compounds, such as for example hydrogen peroxide, perborates or percarbonates, are normally used for this purpose, having almost completely displaced the hypochlorites often previously used.
There has been no shortage of attempts in the past further to improve the color quality of surfactants which, despite bleaching, has often been unsatisfactory. For example, it is proposed in WO 93/13113 (Henkel) to enhance the effect of the hydrogen peroxide by using various bleaching boosters, such as for example magnesium ions and the like. Although it has been found in practice that products with a distinctly improved color are obtained, their stability in storage is still far from satisfactory.
Accordingly, the problem addressed by the present invention was to remedy this deficiency by providing a process that would give products which would be light in color immediately after bleaching and which would remain stable, even after prolonged storage at --optionally --relatively high temperatures.